Fujiwara, Sumire , Kim, Woe-Yeon , Suh, Sung-Suk , Kim, Jeongsik , Kim, Yumi , Han, Linqu , David, Karine , Putterill, Joanna , Nam, Hong Gil , Somers, David E. .
Blue-light dependent stabilization of ZEITLUPE requires the LOV domain in Arabidopsis.
Circadian rhythms generated by a circadian clock have significant roles for regulating many physiological phenomena in Arabidopsis. Appropriate regulation of rhythmic cycling of key elements of the clock is essential to maintain robust oscillations. Cyclic oscillation of ZEITLUPE (ZTL) is required to sustain normal circadian cycling via the proteasome-dependent degradation of TIMING OF CAB EXPRESSION 1 (TOC1) which is a core factor of a central oscillator. ZTL is an F-box protein and its cyclic oscillation is post-transcriptionally regulated by the proteasome. In this study, we have identified a novel factor which participates in ZTL regulation. In its absence, the normal four-fold diurnal cycling in ZTL is post-transcriptionally eliminated, resulting in constitutively low ZTL accumulation. Their interaction occurs through the LOV domain in the ZTL N-terminus, which is necessary and sufficient for the interaction. Blue light specifically and strongly enhances the protein-protein interaction which is markedly diminished by mutations in the LOV domain. A C82A transition, implicated in the flavin-dependent photochemistry, eliminates blue-light enhanced binding. Circadian control of message levels of the ZTL-interacting protein, and subsequent cycling of the protein, confers a post-translational rhythm on ZTL protein abundance, defining a novel mechanism to establish and sustain circadian oscillations.
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1 - The Ohio State University, Department of Plant Cellular and Molecular Biology, 038 Rightmire Hall, 1060 Carmack Road, Columbus, OH, 43210, USA
2 - University of Auckland, School of Biological Sciences, Private Bag 92019, Auckland, New Zealand
3 - Pohang University of Life Science and Technology, Department of Life Science, Pohang, Kyungbuk, 790-784, Korea
Presentation Type: ASPB Minisymposium
Location: Continental B/Hilton
Date: Sunday, July 8th, 2007
Time: 4:35 PM